The present inventors have found that 7-[(Z)-2-(2-aminothiazol-4-yl)-2-[(.alpha.-carboxy-3,4-dihydroxybenzyl)oxy imino]acetamido]-3-[(1-carboxymethyl-4-pyridinio)thiomethyl]-3-cephem-4-car boxylate (hereinafter referred to simply as BO-1463) has good antibacterial activities against Gram-positive bacteria and Gram-negative bacteria, and have filed a U.S. patent application (Ser. No. 07/028,576 now 4880796) concerning BO-1463. BO-1463 is a cephem compound expected to practically be used as a curing agent for bacterial infections.
However, the description of the specification of the U.S. Patent Application refers nothing about optically active compounds based on the asymmetric carbon of a (.alpha.-carboxy-3,4-dihydroxybenzyl)oxyimino group substituting at the acyl side chain, and such optically active compounds or their crystalline have not been synthesized.
.beta.-lactam antibiotics exhibit selective toxicity against bacteria only and present no substantial effects against animal cells, and they have been widely used for the treatment of infectious diseases caused by bacteria as antibiotics having no substantial side effects. Thus, they are highly useful drugs.
However, in recent years, glucose non-fermentative Gram-negative rods, particularly Pseudomonas aeruginosa have been frequently isolated from immuno-compromised patients, as causative organisms of refractory infections and have posed various problems. Therefore, it has been desired to develop an antibacterial agent having an improved activity against such bacteria.